1. Field of the Invention
The present invention relates to a heat sink which may be adapted for use in a heat dissipation of an electronic equipment and the like having a heat generating part which needs to be cooled.
2. Related Art
In recent years, an electronic element such as a semiconductor device and the like to be mounted on various electronic or electric equipment such as a personal computer and the like has been densely integrated, the output thereof has become large, and an amount of heat generated therefrom has increased. It has become an important technical problem which is to be solved to cool such an electronic equipment having heat generating parts, and the improvement in such cooling techniques attracts people""s attention. As a method for preventing the heat generating electric element (hereinafter referred to as xe2x80x9cheat generating partxe2x80x9d) from being overheated, there is known a method of lowering the temperature of the air inside the body encasing the electronic equipment by a fan attached thereto so as to discharge the air and cool the heat generating part, or a method of cooling the heat generating part by a cooling member which is attaching to the heat generating part and removes heat from the heat generating part.
The cooling member which is attached to the heat generating part is generally called as a heat sink, and is often used in the form of a plate member made of a material being excellent in thermal conductivity such as copper, aluminum and the like. In order to efficiently discharge the heat which is transferred from the heat generating part to the plate member as the cooling member, heat radiating fins are often integrally formed with the plate member. In addition, there is also an embodiment in which a heat pipe is attached to the above-mentioned plate member to transfer the heat from the plate member to a prescribed place, and furthermore, heat radiating fins are attached to the portion in the prescribed place which is separated from the heat generating part, thus transferring the heat and then dissipating therefrom the transferred heat.
In addition, in order to improve the uniformity in heat absorption of the plate member, a heat pipe is sometimes attached to or buried in the plate member. Improvement of the uniformity in heat absorption of the plate member makes it possible to more efficiently absorb the heat generated by the heat generating part.
A heat pipe which has been used up to now is briefly described. The heat pipe includes a container having a hermetically sealed cavity and a working fluid enclosed in the container. The heat pipe has generally a heat absorption (i.e., evaporator) side and a heat radiation (i.e., condenser) side. The heat pipe has a function of moving heat from the evaporator side to the condenser side by means of a phase transformation of the working fluid enclosed in the cavity from a gaseous phase to a liquid phase or from a liquid phase to a gaseous phase, and the movement of thus phase-transformed working fluid inside the cavity.
More specifically, in the heat absorption side of the heat pipe, the working fluid enclosed inside the hermetically sealed cavity is evaporated by the heat thermally transferred from the heat generating part through the material of the container forming the heat pipe, and the vapor of the working fluid which has been transformed in phase passes through the inside of the cavity and moves to the condenser side of the heat pipe. In the condenser side, the vapor of the working fluid is cooled and returns to the liquid phase. The working fluid which has returned to the liquid phase flows back to the evaporator side. As described above, movement of heat is performed by a phase transformation and movement of the phase-transformed working fluid. In order to make it easy to transform the working fluid in phase, the cavity is degassed and hermetically sealed.
Since a cooling structure (i.e., cooling device) in which the cooling member is attached to the heat generating part, and heat radiating fins are further attached to the cooling member can efficiently cool the heat generating part, although it is comparatively small in size, the cooling structure is expected to be an effective cooling means.
In recent years, a marked tendency may be seen to make small in size various kinds of electronic equipment having semiconductor devices which need to be cooled. Accordingly, there is a trend to restrict the space in which the cooling structure used for cooling the part is to be installed.
In order to realize a small-sized (space-saving) cooling structure, it is necessary to realize a more efficient heat dissipating means. Moreover, since an amount of heat generated by an electronic equipment has increased, it is required to develop a cooling structure capable of effectively dissipating a large amount of heat. Such a cooling structure has not yet been proposed.
An object of the present invention is to provide a cooling structure which is compact, however, simultaneously can realize an excellent cooling performance, and furthermore, can dissipate a large amount of heat.
The present invention has been made in order to attain the above-mentioned object. According to the present invention, there is proposed a first embodiment of a heat sink comprising;
(a) a plate-shaped heat pipe including an upper plate member and a lower plate member to form a hermetically sealed cavity, and a working fluid enclosed therein, and
(b) at least one heat radiating fin integrally formed with said upper plate member on an outer surface of said upper plate member.
According to the present invention, there is proposed a second embodiment of a heat sink, wherein a heat transferring metal column for joining said upper plate member and said lower plate member with each other in said cavity of said heat sink is integrally formed with said lower plate member on a portion corresponding to a heat absorbing portion of said plate-shaped heat pipe.
According to the present invention, there is proposed a third embodiment of a heat sink, wherein a total area of side wall portion of said heat transferring metal column is larger than a sectional area of said heat transferring metal column.
According to the present invention, there is proposed a fourth embodiment of a heat sink, wherein at least one pressure resisting metal part is integrally formed with said upper plate member and/or said lower plate member in said cavity of said heat sink.
According to the present invention, there is proposed a fifth embodiment of a heat sink, wherein each of said heat radiating fin and said pressure resisting metal part comprises at least two portions or a single portion, and said at least two portions are intermittently arranged in a radial manner, whereas said single portion is continuously arranged in a radial manner.
According to the present invention, there is proposed a sixth embodiment of a heat sink, wherein each of said heat radiating fin and said pressure resisting metal part comprises at least two portions or a single portion, and said at least two portions are intermittently arranged in a shape of a swirl, whereas said single portion is continuously arranged in a shape of a swirl.
According to the present invention, there is proposed a seventh embodiment of a heat sink, wherein a wick is disposed in said cavity of said heat pipe.
According to the present invention, there is proposed a eighth embodiment of a heat sink, wherein an electrically driven fan is disposed at a location facing said heat radiating fin.